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采用WRF中尺度模式对2008年6月长江中下游地区一次大暴雨过程进行数值模拟,并利用模式高分辨率资料进行初步诊断分析。结果表明:此次暴雨过程是在高、低空急流和低涡切变线的共同作用下发生的;西南低空急流不但是产生暴雨所需的水汽输送带,也是造成暴雨强对流所必需的位势不稳定能量的输送者。水汽分析表明,水汽通量散度辐合中心与强降水中心有较好的对应关系。能量分析表明,高能舌前部、能量锋区南缘靠近能量锋区处和低空急流左前方三者叠加的区域是暴雨的易发区;高、低空急流及低涡切变线是此次暴雨的动力触发机制,一方面,高层负涡度的辐散和中低层辐合相叠置,使气旋和中尺度低涡切变线进一步加强;另一方面,低层不稳定能量的释放使降水得以维持和加强。
The WRF mesoscale model was used to simulate a heavy rainfall process in the middle and lower reaches of the Yangtze River in June 2008 and to make preliminary diagnosis and analysis using high resolution data. The results show that this rainstorm process takes place under the combined effect of high and low level jet and shear vortex line. The low-level jet stream in the southwest is not only the water vapor conveyer belt required to generate heavy rainfall, but also the potential for strong convective storm Carrier of unstable energy. The analysis of water vapor shows that the convergence of water vapor flux divergence center and the strong precipitation center have a good correspondence. Energy analysis shows that the front of the high energy tongue, the southern edge of the energy front close to the front of the energy front and the left front of the low-level jet are prone areas for rainstorms; the high and low-level jet and shear vortex are the heavy rain On the one hand, the divergence of high-level negative vorticity overlaps with the middle-low level convergence and further enhances the cyclone and mesoscale vortex shear line; on the other hand, the release of unstable low-level energy enables precipitation Maintain and strengthen.